Field of the Invention
The present invention relates to a solid state image sensor, a method of manufacturing a solid state image sensor, and an image capturing system.
Description of the Related Art
Solid state image sensors and display apparatuses use optical elements such as microlens arrays as disclosed in Japanese Patent Laid-Open No. 2007-335723. Japanese Patent Laid-Open No. 2007-335723 discloses a technique of providing microlenses, each having a shape called a teardrop, in a solid state image sensor to efficiently focus light entering from oblique directions onto light-receiving units. Such a microlens is shaped to have a curved shape tapering to the outside of the solid state image sensor and having a vertex at an outside end portion when viewed in a planar view.
In principle, however, each microlens having the teardrop shape disclosed in Japanese Patent Laid-Open No. 2007-335723 cannot cause part of light entering the microlens to enter the corresponding light-receiving unit, that is, cannot contribute to the focusing of light, depending on the incident position of light. In addition, such light is likely to enter the regions of adjacent pixels and become stray light, leading to deterioration in the sensitivity and image quality of the solid state image sensor.